1. Field of the Invention
The present invention relates to a semiconductor memory device, in particular, an SRAM and a method of fabricating the same.
2. Description of Background Art
A six transistor-type SRAM comprises memory cells including two load transistors, two driver transistors, and two transfer transistors. Active regions of each memory cell are isolated from active regions of the adjoining cells by an element isolation region comprising a field oxide layer and the like.
A phenomenon in which current flows between the element isolation regions is referred to as punch-through. Punch-through causes malfunction of the SRAM. According to the demand for a reduced cell size, the width of the element isolation region has become narrower. Punch-through occurs more easily as the width of the element isolation region becomes narrower.